Lifter Rattle Question

I have an '87 XJ with 260k on it. I replaced the RMS and the rod bearings a few months ago. From what I could see of the cam it looks to be in pretty good shape. 60% of the time when I crank my jeep, after it's been sitting a day or so I get some lifter rattle for about 10 seconds. Then, after the jeep is good and warm. If I rev it, I get lifter rattle when I blip the throttle. My question is, before replacing the lifters should I try a different oil weight? If so what should I try? I think I have 10w 40 in it right now. Could it be the oil pump isn't putting out enough pressure? I don't have a pressure gauge yet.. just idiot light. Lastly, would it be possible on this 4.0 to replace the lifters without pulling the head? My dad told me about some kind of long grabber you can use on V shapped engines without pulling the intake.

Does the lifters rattling do a lot of damage? I get that when mine is not all the way warmed up, and I'm driving right before it shifts it revs freely for a slight moment, and I hear a bad rattle. It almost seems like the oil just hasn't reached the top of the motor yet, but pressure is perfect, and jeep runs GREAT. You can try an additive that touts quieting engine noise, but I am still not sure how to cure it except going really easy on the throttle until it is fully warm.

I don't think it does damage. but it means your valves are not opening all the way because the lifter isn't "pumped" up..
I do get a kind of knock/bump when my engine fires up.. which I thought was rod bump.. and is why I replaced the rod bearings. I hope my noise isn't coming from a main bearing.. the bearing on the rear main cap looked great..

Keep your eye on yer water pump, bro... Just in case...

A few guys use a combination of Marvel mystery oil and Lucas oil additive to cure their rattles... I like both of those products, and they have never been accused legally of being snake oil which means they have never blown up anyone's motor. I am gonna give it a shot. I am half way between changes, so I should have a little room to top it off with both. I'll keep you posted on my results.

mine does it also its a 90 with 185,000 I think it is the timing chain but im not sure it has a good amount of play in it

ceb0217 said:

mine does it also its a 90 with 185,000 I think it is the timing chain but im not sure it has a good amount of play in it

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I felt of my timing chain when I had the oil pan off, I don't remember the exact play but it was at the end of the service limit.. but close to being within spec.

xj88superjeep said:

Keep your eye on yer water pump, bro... Just in case...

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My WP is new.. replaced by the previous owner, how would it be related?

stephenspann27 said:

My WP is new.. replaced by the previous owner, how would it be related?

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It will knock and rattle when the bearings go bad... I let the one on my 88 go until it was howling before I finally had some free time to replace it. It will definitely sound like you blew up your motor if you aren't familiar with the sound.